TECTONOPHYSICS

ELSEVIER  Tectonophysics 260 ( 1996) 291-323

Paleogeography and structure of the centrai Mediterranean:
                    Sicily and its offshore area

                   R. Catalano, P. Di Stefano, A. Sulli, F.P. Vitale

                Dipartimento di Geologia e Geodesia. Università di Palermo. Via E. Tori 91.90128 Palermo. Italia
                                              Received 3 July 1995: accepted 20 November 1995

Abstract

    The geology of the mainland and offshore of Sicily is illustrated by a few geologie sections and seismic profiles across
the late Cenozoic orogenic belt of centrai and western Sicily and across the Sardinia Channel and Sicily Straits. This belt is
the result of several tectonic events. Deformation involved mainly the sedimentary cover of the old African continental
margin characterized by a broad basinal domain, flanked along its external (southern) margin by a shallow-water carbonate
platform attached to Africa in the Triassic. Compressional deformation started in the more internai basinal rock assemblages
overlying a thinned crust. The most important structural characteristic of the early phase of thrusting is the duplex pile
forming the bulk of the chain in Centrai Western Sicily. The structure consists of a basai allochthon, made up of Permian to
Middle Triassic layers, an intermediate duplex wedge, composed of competent Mesozoic carbonates, and a roof complex,
including Upper Mesozoic-Lower Tertiary less competent rocks. Large-scale clockwise rotation of the thrusts accompanied
transpressional movements in the hinterland during the Pliocene. Right oblique reverse faults modified the previous tectonic
contacts between the allochthons in the hinterland zones. Contemporaneous south-directed imbrications affected the southern
external areas, progressively incorporating foreland and piggyback basins. Development of the Gela Thrust System appears
to be linked to the transpressional event; its accretion is also related to contemporaneous underthrusting at deeper levels of
Mesozoic carbonate substratum. The older buried thrust sheets were pushed up to the surface breaching the deformed
Tertiary cover of the Gela TS. Northwards in the beh post-Messinian norma) growth faults opened half graben whose
sedimentary fili underwent structural inversion. Alternation of extension and compression tectonics characterizes the Sicilian
continental margin in the last million years.

l. lntroduction                                               In this sector of the Mediterranean area the main
                                                           compressional movements, after the Paleogene
   The studied area, located in the centra! western        Alpine orogeny, began with the latest Oligocene-
Mediterranean, is a segment of the Alpine collisional      Early Miocene counter c!ockwise rotation of Cor-
belt developing along the Africa-Europe plate              sica-Sardinia, believed to represent a volcanic are,
boundary. It links the African Maghrebides with            and its collision with the African continental margin
Calabria and the Apennines, and extends from the           (Bellon et al., 1977; Channell et al., 1979; Dercourt
Corsica Sardinia block across the mainland of Sicily       et al., 1986). This collision is generally considered
to the Pelagian Platform; part of the chain collapsed      the primary cause for most of the contractional de-
with the opening of the centrai south Tyrrhenian sea       formation in the Southem Apennine-Sicilian thrust-
(Fig. 1).                                                  belt. The most accepted group of models postulates

0040-1951 /96 j$15.00 Published by Elsevier Science B. V.
SSD1 0040-1951 (95)00 196-4